1. Field of the Invention
The present invention relates generally to ePaper and in particular to ePaper writing. Still more specifically, the present invention relates to a method and apparatus for writing ePaper using a stamp.
2. Description of the Related Art
Electronic reusable paper (ePaper) is a display material used to present information and has many of the properties of paper. Electronic reusable paper stores an image, is viewed in reflective light, has a wide viewing angle, is flexible, and is relatively inexpensive. Unlike conventional paper, however, it is electrically writeable and erasable. Although projected to cost somewhat more than a normal piece of paper, a sheet of electronic reusable paper could be re-used thousands of times. Electronic reusable paper has many potential applications in the field of information display including digital books, low-power portable displays, wall-sized displays, and fold-up displays.
Electronic reusable paper utilizes a display technology, invented at the Xerox® Palo Alto Research Center (PARC), called “Gyricon.” A Gyricon sheet is a thin layer of transparent plastic in which millions of small beads, somewhat like toner particles, are randomly dispersed. The beads, each contained in an oil-filled cavity, are free to rotate within those cavities. The beads are “bichromal,” with hemispheres of two contrasting colors, such as black and white, red and white, or blue and yellow, and charged so they exhibit an electrical dipole. When voltage is applied to the surface of the Gyricon sheet, the beads rotate to present one colored side to the viewer. Voltages can be applied to the surface of the Gyricon sheet to create images, such as text and pictures. The image will persist without a voltage applied for a significant period of time.
There are many ways an image can be created in electronic reusable paper. For example, Gyricon sheets can be fed into printer-like devices that will erase old images and create new images. Printer-like devices can be made so compact and inexpensive that one can imagine carrying one in a purse or briefcase at all times. One envisioned device, called a wand, could be pulled by hand across a sheet of electronic reusable paper to create an image. With a built-in input scanner, this wand becomes a hand operated multi-function device, such as a printer, copier, fax, and scanner. The wand device writes the image one line at a time.
For applications requiring more rapid and direct electronic updates, the Gyricon material might be packaged with a simple electrode structure on the surface and used more like a traditional display. An electronic reusable paper display could be very thin and flexible. A collection of these displays could be bound into an electronic book. With the appropriate electronics stored in the spine of the book, pages could be updated at will to display different content.
For portable applications, an active matrix array may be used to rapidly update a partial- or full-page display, much like what is used in today's portable devices. Gyricon displays do not require backlighting or constant refreshing and are brighter than today's reflective displays. These attributes will lead to Gyricon's utilization in lightweight and lower-power applications.